riot3 svg viewBox

Example of error working with viewBox

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/riot/3.0.0/riot+compiler.min.js"></script>
<script  type="riot/tag">
  <container>
    <svg riot-viewBox="{viewBox}"> 
        <circle  riot-r="{r}" riot-cx="{x}" riot-cy="{y}" fill="red"/>
    </svg>

    this.viewBox='0 0 200 200'
    this.r=20
    this.x=30
    this.y=30 
    
  </container>
</script>
<div id="container"></div>

CSS

html, body, svg{
  width:100%;
  height:100%;
  padding:0px;
  margin:0px;
}

JavaScript

riot.mount('#container','container');
var svg = document.querySelector('svg')